In a computing system, reconnaissance is often a typical first step in a targeted attack. An attacker must often learn of available services, software, and operating system configuration in order to determine how to best infiltrate a given system. This information can often be gathered directly or indirectly via specifically crafted network requests.
Current standard practices are to limit the information available to attackers via network services. For instance, a web server can be configured to refrain from revealing its name, version number, or installed modules. However, not all server applications can be configured in this way, and not all protocols allow for such minimal server information. In addition, attackers can often use other indirect information to determine server operating characteristics.